C to RISC$-$V assembly conversion. Consider each of the

following high$-$level $($C$)$ code snippets. Convert them to RISC$-$V assembly. Translate the

code directly as it is $($do not rewrite the high$-$level code$).$

For this problem only, do not use the stack $$ you will correct this $($i$.$e$.,$ use the stack$)$ in the

next problem.

Function calls:

a$)$ C code:

int main$()\{$

$...$

int y $=$ subtract$(7,3)$; $//$ y is in s$5$

$...$

$\}$

int subtract$($int x$,$ int w$)\{$

int result; $//$ result is in s$7$

result $=$ x $$ w;

return result;

$\}$

b$)$ C code:

$//($same code as above, except main makes $2$ function calls$)$

int main$()\{$

$...$

int y $=$ subtract$(7,3)$; $//$ y is in s$5$

int w $=$ subtract$(8,20)$; $//$ w is in s$6$

$...$

$\}$

int subtract$($int x$,$ int w$)\{$

int result; $//$ result is in s$7$

result $=$ x $$ w;

return result;

$\}1.[40$ pts total, $20$ pts each$]$ C to RISC$-$V assembly conversion. Consider each of the following high$-$level $($C$)$ code snippets. Convert them to RISC$-$V assembly. Translate the code directly as it is $($do not rewrite the high$-$level code$).$

For this problem only, do not use the stack $-$ you will correct this $($i$.$e$.,$ use the stack$)$ in the next problem.

Function calls:

a$)\backslash (\backslash$mathbf$\{$C$\}\backslash )$ code:

$```$

int main$()\{$

$...$

int y $=$ subtract$(7,3)$; $//$ y is in s$5$

$...$

$\}$

int subtract$($int x$,$ int w$)\{$

int result; $//$ result is in s$7$

result $=$ x $-$ w;

return result;

$\}$

$```$

b$)\backslash (\backslash$mathbf$\{$C$\}\backslash )$ code:

$```$

$//($same code as above, except main makes $2$ function calls$)$

int main$()\{$

$...$

int y $=$ subtract$(7,3)$; $//$ y is in s$5$

int w $=$ subtract$(8,20)$; $//$ w is in s$6$

$...$

$\}$

int subtract$($int x$,$ int w$)\{$

$``````$

int result; $//$ result is in s$7$

result $=$ x $-$ w;

return result;

$\}$

$```$

$2.[40$ pts total, $20$ pts each$]$ Functions and the stack $-$ saving preserved registers on the stack. Rewrite the RISC$-$V assembly code from problem $1,$ but this time use the stack as needed to save and restore registers. This is the correct way to write a function.

$3.[20$ pts total$]$ Saving preserved and non$-$preserved registers on the stack. Consider the following two function calls. Notice that func$1$ uses one of its arguments $($b$-$i$.$e$.,$ a$1)$ after it makes a function call to func$2.$

a$)[\backslash (\backslash$mathbf$\{5\}\backslash$mathbf$\{$~ p t s $]\}\backslash )$ What value does func$1$ return when it is called as: func$110,20$

b$)[15$ pts$]$ Perform the following steps to convert this high$-$level code to assembly.

$1.$ Write the code without worrying about the stack or registers that get overwritten.

$2.$ Now, modify the code to use the stack to save$/$restore registers in the code.

int func$1($int a$,$ int b$)\{$

int val $=7$; $//$ val is in s$2$

if $($val $$ a$)$

val $=$ val $+$ func$2($b$,$ a$)$;

val $=$ val $-$ b;

return val;

$\}$

int func$2($int x$,$ int w$)\{$

int result; $//$ result is in s$2$

result $=$ x $|$ w;

return result;

$\}$